WoW- Casual basically defines the current players as well as gameplay. If you can get someone to RAF you then you can hit 85 in 2 or 3 days from just doing dungeons. I tend to just sit in the nearest lake and fish(you can make gold off of this) though just for the hell of it or go and do easy dungeons for greens to disenchant and level my enchanting or I go and collect herbs to sell to people on the auction house. So far I have been collecting a bunch of stuff mainly pets/mounts/achievements/"trophies". :P
I've played WoW off and on (mostly off) since vanilla. I might just return and try out MoP. I haven't heard anything about MoP, as I stopped playing Cata before it came out.
I'll check it out again I guess.
As for Runescape, I loved that game when I was younger and have checked in on it every few months for the past 10 years or so. I just can't play with the Evolution of Combat and RS3. It isn't the game I enjoyed any more. It's also an insane time sink if you plan on getting anywhere in the game and (not sure of the situation now) when you finally do get somewhere, most of the others botted their way there anyway.
When I said "casual", I didn't mean it in the usual sense. I'm just looking for something that has aspects to it that don't always revolve around hitting max level and getting the best gear.
hmm.. did you already consider Lotro?
for crafters and casual adventurers it really is a very complete adventure. fishing, wander around, join in the roleplay, make and play your own music in game as a bard, go watch wars etc... i feel it is a sort of western mabinogi.
Be warned - I am a major player of Regnum Online the mmo. I've been playing it for about 2 years and rarely go without logging in at least once a day. You can also look at good alternatives to Regnum such ase Aion online and Aika Online.